the fuel priming problem sounds like the tank isn't getting enough pressure!
as you had a blocked stinger it stands to reason you might have a blocked prssure nipple too, you need to remove the pipe, cover the stinger & blow down the end, you should get a steady stream of air coming back into your face, if not then clean it out til you do
the cutting out over half throttle sounds like a tuning issue, i can't tell from what you've said if its too rich or too lean but try resetting the HSN to about 2.5 turns out (factory is 3 turns & this is rich) & see how you go
as for the dirt in the engine without seeing how much & where it got to i can't say if it will be OK or not, just clean it all out and lightly oil everything before you try running it again!

hopefully you have gotten away with it & have learned the 3 golden rules of Off-Road racing

AIR-FILTER
AIR-FILTER
AIR-FILTER

i learned that the hard way myself back in my dirtbike days

good luck dude